An anti-microbial composition effective for use with both human and animal topical surfaces, including sterilization of tissue, skin and body cavities, and for disinfection/sterilization of medical devices/instruments, at or below 60xc2x0 C., is described.
Medical, dental and other instruments are often made of high quality stainless steel that can be cleaned and sterilized between uses for different patients by high temperature steam under pressure. This sterilization procedure is quick, reliable, odorless, non-toxic and inexpensive. In contrast to this situation, more and more devices are now made of heat-sensitive plastic, polymers, glass lenses and electronic components. These flexible, or rigid lensed devices allow relatively non-invasive diagnostic and treatment procedures within the body. The non-invasive procedures allowed by these heat-sensitive instruments are responsible for great advances in medical practice. During use, these instruments can be contaminated with potentially deadly pathogens such as the Human Immunodeficiency Virus (HIV), hepatitis viruses, and multiply antibiotic drug-resistant bacteria, including mycobacteria. For these reasons, it is imperative that these heat-sensitive devices be disinfected or sterilized prior to each use. The chemical germicides available for sterilization of heat-sensitive instruments have in the past had many problems that made their use difficult.
The antimicrobial properties of hydrogen peroxide have been known for many years. However, 6% hydrogen peroxide, efficacious at a low pH which is deleterious to many medical device materials, requires a minimum of 6 hours at room temperature to pass the standard Association of Official Analytical Chemists (AOAC) Sporicidal Test defining test for liquid chemical germicides in the United States. The antimicrobial properties of peracetic acid are also well known. Peracetic acid has a very sharp pungent odor, and is known as a tumor-promoting agent when tested on mouse skin. For these reasons, the use of peracetic acid as a chemical sterilant is limited to low concentrations used with enclosed systems.
Antimicrobial synergism between hydrogen peroxide and peracetic acid is a well established fact. Such compositions are prepared by mixing hydrogen peroxide and acetic acid to give equilibrated solutions of hydrogen peroxide, acetic acid, and peracetic acid. There is a great deal of scientific and patent literature regarding hydrogen peroxide-peracetic acid solutions for sterilization. By way of example only, Minntech Corporation of Minneapolis, Minn., has a kit or sterilization console for disinfecting with hydrogen peroxide-peracetic acid solutions (U.S. Pat. No. 5,400,818). However, this combination is limited by the same problems of pungent odor and potential toxicity as peracetic acid alone. This often means that such formulations are used at such dilute concentrations that rapid sporicidal activity is lost, or the solutions are limited to enclosed systems that contain the pungent fumes.
STERIS Corporation of Mentor, Ohio, markets a System 1 product. This uses a low concentration of peracetic acid (about 0.2%) contained within a machine, and is heated to 122xc2x0 F. to achieve rapid sterilization. The relatively low peracetic acid concentration is broken down by the high temperature, limiting it to one single use cycle. The heated, enclosed, machine system utilizing a single-use sterilant charge is expensive and requires exclusive use of STERIS 20 sterilant and monitoring products.
Another cold sterilant of STERIS Corporation is described in U.S. Pat. No. 5,350,563. It uses the combination of a perborate and a mixture of a rapid acting acetyl donor and a slow acting acetyl donor. Similarly, the assignee of the present applicant has an earlier U.S. Pat. No. 6,096,348 on a quick acting chemical sterilant based upon the combination of hydrogen peroxide and dibasic carboxylic acids with a carboxylate salt buffering system. While the latter two described compositions have efficacy, they are somewhat complex and with respect to the common assignees ""348 patent such may be perceived by some as incompatible with certain device materials because of the acid pH range.
As well, no one to date has developed a low temperature disinfectant/sterilant for instruments that can also be used as an effective antimicrobial for human and animal topical surfaces such as tissue, skin and body cavities. This has several advantages. First, the more universal applicability appeals to some consumers. Secondly, the system is simpler in component design than either of the above-described systems and therefore should involve less opportunity for failures. Other beneficial characteristics include fewer toxicity or environmental issues, and a potential for economical savings.
It is a primary objective of the present invention to provide a cold sterilant/disinfectant which has universal applicability in the sense that it can be used on both topical surfaces and on medical devices, such as endoscopes. The present invention provides this more universally applicable system with a less complex ingredient system, thus decreasing the risk of failure and the expense to prepare. These latter advantages assure real consumer benefits.
This invention relates to a powdered mixture, delivered as a loose powder, compressed powder or tablet, of a perborate, one or more novel acyl and/or aroyl donors (other than acetyl), a buffering system of one or more buffers, and preferably a surfactant which facilitates microbial kill efficacy. The result when mixed with water is a cold temperature effective sterilant (18xc2x0 C.-60xc2x0 C.) which allows the pH to rise to about 9 for rapid formation of one or more peroxycarboxylic acids (other than peracetic acid) and then drop to about 7.5xc2x10.5 for sustained stability and microbial kill.